Efficacy of intravenous amiodarone in the management of paroxysmal or new atrial fibrillation with fast ventricular response.

We tested the efficacy of intravenous amiodarone (5 mg/kg) in slowing ventricular response and/or restoring sinus rhythm in 26 patients with paroxysmal or new atrial fibrillation with fast ventricular response. There were 16 men and 10 women with ages ranging from 35 to 84 years, mean 63 years. Intravenous amiodarone initially slowed the ventricular response in all patients from 143 +/- 27 to 96 +/- 10 beats/min (P less than 0.001). Twelve patients (46%) reverted to sinus rhythm within the first 30 min (range 5 to 30 min, mean 14 +/- 9 min). One patient reverted to atrial flutter after 10 min and 40 min later to sinus rhythm. Six patients (23%) converted to sinus rhythm after 2 to 8 hr and in these 6 cases, the initial slowing in ventricular response obtained with amiodarone persisted until conversion. Seven patients (27%) did not convert to sinus rhythm following amiodarone administration and they required further medical therapy to slow the ventricular response and/or to convert to sinus rhythm. No serious side effects from drug administration were noted. Intravenous amiodarone appears as a highly effective medication in the conversion or control of new onset atrial fibrillation with fast ventricular response.